Based on experience, the author analyzes the causes of wrinkling in the printing of books and publications as follows.
First, the paper problem caused the wrinkling of printed products. 1. The moisture content of the paper is unevenly distributed: if the water content is greater than the middle part (ie, the hourly edge), wrinkling of the dragging part will occur; if the water content is less than the middle part, (ie, tight-edge paper), there will be wrinkling in the middle.
2. The moisture content of the paper is too large; if the moisture content of the paper is too large, the deformation of the pressure during the imprinting process will produce branching wrinkles that extend from the gargle to the tip.
Second, the mechanical adjustment factors cause wrinkling of the printed product. 1. The paper feeding roller on the paper board is not uniform in pressure or the tension of the paper feeding belt is uneven: The paper is in the conveying process due to improper pressure adjustment of the paper feeding roller or uneven feeding belt tension. Due to the influence of the axial force in the middle, it may swell or be skewed, which may cause the product to wrinkle when it is imprinted.
2. Improper Paper Transfer: Before the paper enters the imprinting system, the flatness of the paper is damaged in the handover process, so the paper is creased during the imprinting process.
3, the impression force of the impression cylinder grippers is inconsistent or uneven.
4. The ink on the surface of the embossing cylinder is too thick to make the paper unsmooth.
In the printing process, once the printed product is found to be wrinkled, it should be immediately stopped to analyze the cause of wrinkling. The method of observing the wrinkle rule of the product is generally adopted. The reason for the paper is that the wrinkling position of the product is changed, and the position of the wrinkle caused by improper mechanical adjustment is basically fixed. It is also possible to use other types of paper for the trial printing method. If the wrinkling site is not changed, it can basically be determined as a mechanical factor. If there is a change, it is a paper factor. After the cause of the wrinkling is analyzed accurately, the drug can be prescribed. The solution is as follows:
1. The wrinkling phenomenon caused by the paper factor The paper is hung on the paper machine for about 6 hours to make the water content of each part of the paper consistent.
2. One of the causes of the wrinkling phenomenon caused by mechanical adjustment factors: Tighten and tighten the tension of each paper conveying belt, adjust the pressure of each paper feed roller not too large or too small, and do not tilt.
The second reason is to adjust each handover link to ensure the balance and reliability of the handover process.
The third reason is to level the dental pad, and then turn the machine to the position of the crucible. Place a 0.3 mm thick piece of paper between the set screw and the positioning block. Use a sheet of basis weight of 80 g/m2. The paper strips were tested one by one from the middle to the two sides, and it was appropriate to measure the strength of the teeth in a way that the force could not be extracted properly. At the same time, the grip force of each tooth was kept uniform.
The fourth reason: use gasoline to clean the ink on the surface of the impression cylinder.
From the above analysis, it can be seen that the causes of product wrinkling in book printing are various. Therefore, we need to conduct comprehensive analysis and accurate judgments in order to achieve rapid and accurate troubleshooting.
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